SummarySerial transfer of foci on the CAM through at least 3 transfers is confirmed. Significant titers of antibody were found in a high percentage of recipient eggs 5 days after inoculation of spleen cells from an immunized chicken. The transfer of cells from the CAM of these eggs to other eggs resulted in development of foci, but the proportion of eggs with detectable antibody declined rapidly after the first transfer. The presence of antigen in the eggs inoculated with spleen cells from immunized chickens did not stimulate antibody formation. Finally, although both spleen cells and buffy coat cells yielded large numbers of foci, formation of antibody on the CAM was consistently greater with the inoculation of spleen cells from immunized donor chickens.